1. Field of the Invention
The present invention relates to an apparatus and method for handling a charged particle beam in a scanning electron microscope, X-ray microanalyzer, electron beam exposure system or the like.
2. Prior Art
In a charged particle-beam handling apparatus employed in a scanning electron microscope or electron beam exposure system, it is of great importance to correct the astigmatism of a charged particle beam on a sample or object for enhancing the precision and resolution thereof.
It has been customary heretofore for the user to make the necessary correction of the astigmatism through his own visual judgment of the quality of an image on the screen of a cathode ray tube.
It however requires a high degree of skill and a considerably long time for the user to make himself acquainted with such a process of correction, as he must simultaneously adjust both the direction and amount of the astigmatism by means of astigmatic correction devices relying solely on his visual sense in a trial-and-error mode. This imposes a heavy burden on the user.
These difficulties arise out of the fact that the direction and amount of the astigmatism are quantitatively unknown. If these parameters were quantitatively measurable, it would become possible to make correct adjustment of the correction device in accordance with the values measured.